1. Field of the Invention
The present invention relates generally to supplying voltage in a semiconductor device, and more particularly, to conducting an auxiliary current at a supply node to prevent a voltage spike at the supply node for supplying a stable voltage.
2. Description of the Related Art
In general, an electronic device operates with a voltage externally supplied as a power source. In particular, a semiconductor device includes internal voltage generators that generate internal voltages that are each higher or lower than the externally provided voltage to perform operations. For example, a semiconductor memory device generates write/read voltages from an externally supplied voltage for performing write/read operations.
FIG. 1 illustrates a conventional voltage supply apparatus 100 for supplying a voltage to a plurality of current consuming units 120-1, 120-2, and 120-3. The voltage supply apparatus 100 includes a voltage supply unit 110 and a power capacitor 130. The voltage supply apparatus 100 may be formed within a semiconductor device.
The voltage supply unit 110 may be a pad having the voltage applied thereon from an external source. Alternatively, the voltage supply unit 110 may be a voltage generator for generating an internal voltage for operation of the current consuming units 120-1, 120-2, and 120-3. The current consuming units 120-1, 120-2, and 120-3 are internal circuits performing internal operations of the semiconductor device.
The power capacitor 130 stores charge when the voltage supply unit 110 provides the voltage thereon. The current consuming units 120-1, 120-2, and 120-3 consume such charge from the power capacitor 130.
The voltage supply unit 110 ideally supplies sufficient current consumed by the current consuming units 120-1, 120-2, and 120-3 for operation. In addition, the voltage supply unit 110 ideally supplies a uniform and stable voltage level. However, when the current consuming units 120-1, 120-2, and 120-3 begin to consume a large quantity of current, the level of voltage supplied from the voltage supply unit 110 is lowered to result in a voltage drop. Such a voltage drop may deteriorate the performance of the semiconductor device especially for high speed operation.
To prevent such a voltage drop, U.S. Pat. No. 6,504,783 to Jo discloses over-driving a driver of an internal voltage generator before an operating time point of current consumption. However, the internal voltage generator may provide excess current before such an operating time point to result in voltage overshoot which may also deteriorate the performance of the semiconductor device.
Alternatively, the voltage drop at the voltage supply unit 110 may be minimized by increasing the capacitance of the power capacitor 130. However, such increase of the power capacitance 130 undesirably results in increased size of the semiconductor device.